The ruler of a state is a single man (or occasionally, a single woman). He is surrounded by people with guns, any one of whom could easily shoot him. But instead, they follow his orders and shoot other people, or sometimes don’t need to shoot anyone at all—because everyone else is following the ruler’s orders too. But why?

Remember from our discussion of selectorate theory that the ruler needs to have a support coalition on which to anchor his rule. The simplest way to maintain your coalition is by providing benefits to its members—either explicit payments, or privileges, or public goods such as peace and commerce. Perhaps, then, your coalition will follow you instead of another ruler because they believe that you are better at providing benefits than others would be, or that the disruption involved in overthrowing you is not worth the potential gain.

This can be enough, if you have particular administrative or political skill. But it is a relatively fragile basis for your rule; at any time, a competitor might arise who promises to rule more effectively. More seriously, each official has opportunities to ignore your commands if it would benefit him—by receiving bribes, for example. If his only reason for following you is the benefits you provide, he will be much more likely to take bribes or exploit his position in other ways when the opportunity arises. Over time, this kind of venality can totally undermine your rule.

Another common method is to rule by fear—provide benefits to your military enforcers, and use them to cow the rest. This reduces the likelihood of venality, because the official must weigh the potential benefit against the danger of being caught. And realistically, most regimes use a combination of benefits and fear, as they are more effective in combination. (Even in “nice” societies, we rely on the police to deter official corruption—which raises a problem when it is the police who are corrupt. But I digress…) Still, relying on fear is also a fragile strategy—if you ever grow weaker and lose your ability to punish defectors, your entire regime may crumble overnight.

Both providing benefits and threatening punishment lead to a mindset of constant calculation of one’s odds. Better for the regime if it could appeal to a reason why obeying it is the right thing to do, even aside from personal benefit. Such a sense that you ought to obey and that the ruler is entitled to rule is called legitimacy.

Max Weber, that towering genius of sociology, identified three kinds of legitimacy (there are more, but he was focused on the contrast between ancient religious societies and the modern state, his personal enthusiasm): charismatic legitimacy, traditional legitimacy, and rational-legal legitimacy. All three can coexist, and often do, but as pure types they look like this:

Traditional legitimacy is where we follow a given regime because that is what we have always done. The prince succeeds the dying king because no one imagines doing anything different; the peasants pay the tax-collectors (as little as possible) because that’s what their fathers did, and their grandfathers, and everyone they can remember. This does not necessarily imply unthinking obedience; routine behavior can often become its own justification, because changing behaviors can introduce disruption, uncertainty, even chaos and suffering. But traditional legitimacy appeals to history, and one’s obedience to historical norms, as the main justification for continued cooperation with the regime.

All this is thrown into upheaval by the charismatic leader, who appeals not to history, but to his or her own remarkable personal qualities. Often, the charismatic leader claims to be a prophet, either of a god or gods, or of inevitable historical forces, or of a radical new ideology. The charismatic leader challenges the way things have always been done, and gathers followers by force of personality and the momentum of his achievements. Examples would include Martin Luther King, Joan of Arc, George Washington, Julius Caesar, Benito Mussolini, or Adolph Hitler. Clearly, charisma can be used for good or ill.

Ironically, however, a successful charismatic leader cannot sustain a regime by charisma alone. Taxes need to be collected, laws enforced, and supporters rewarded; charisma is a poor means of doing that over long periods, and even if it were, what happens when the charismatic leader dies? The wise charismatic leader will take steps to institutionalize his rule, by building a bureaucracy or a durable support coalition. And certainly once the original leader dies, his successors will tend to justify their rule by appealing to his memory. Thus, Weber notes, the initial charismatic revolution becomes transformed into a traditional regime of its own—or, in more modern times, a rational-legal one.

Weber’s description of rational-legal legitimacy was highly colored by the Germany of his day (the early 1900s), in which the ideal of a disinterested bureaucratic technocracy was supplanting the rule of the old German aristocrats. Thus, he describes a rational-legal regime as based on a bureaucratic class that operated according to laws and regulations, without a hint of self-interest, justifying their activity with the sacred power of the law. The law becomes self-justifying, as an expression of the will of the state. The self-interested rule of traditional aristocrats and the disruptive power of charisma become replaced by the impersonal wisdom of statecraft, executed by a professionalized bureaucracy.

In truth, as I mentioned, most regimes have elements of all three forms of legitimacy (and really, I am tempted to include ideology as a fourth type, since it has its own unique characteristics and doesn’t fit neatly into Weber’s schema). Any dictator worth his salt will try to create a cult of personality; hence, Kim Jong Il claiming to be a champion archer and athlete. Similarly, in the United States, much of the populace reveres the Founders as a sort of secular pantheon. And bureaucracy was known as far back as ancient Egypt and Mesopotamia, though it was not professionalized as Weber would like.

More importantly, any form of legitimacy imposes constraints. The ruler must act, at least in public and at least most of the time, in ways that are consistent with the claimed basis of the regime’s legitimacy. Otherwise, the manifest hypocrisy will erode the feeling of obligation among the citizens that legitimacy is meant to create. The fall of the Soviet Union is perhaps the most spectacular example of recent times, coming as it did after the people had grown cynical of a ruling class that mouthed the platitudes of Communism without providing social equality or development.

Speaking of which, even well-entrenched legitimacy will only take you so far. If a legitimate king puts his support coalition at risk with reckless policies or defeat in war, they will only stick with him for so long before inventing a pretext to replace him, crown or no crown. Similarly, if the laws are not being enforced and no one fears the regime, it will be only a matter of time before petty opportunism snowballs into something more serious.

Still, legitimacy is supremely important. It is the glue that holds societies together. It allows regimes to rule effectively without imposing a costly police state, as most of the people will respond with quasi-voluntary compliance, in the phrase of Margaret Levi.

For writers, legitimacy can be a powerful theme. Does the regime have the support of the people? On what basis does it claim the right to rule? Do your protagonists live under a legitimate but feckless ruler, such that they must choose between respecting their traditions and physical survival? How might a regime seek to generate more legitimacy? Does a ruler behave as he should in public, but violate his claimed principles in private? How might an external enemy, or a rebel group, or a treacherous nobleman, attack a regime’s legitimacy?